prokaryotic mRNA in frozen tissues or fluids

> After how long can prokaryotic mRNA found in frozen tissues or body fluids
> of an animal (eg. fish) be used in a successful reverse transcription
> polymerase chain reaction(RT-PCR)?
>As long as the tissue is handled and stored properly,eg. RNase free
containers and a steady -80, it should be good for at least 6 months to
one year or more.
Have fun. Kevin.